It is often desired to establish a flow of gas. For example, a flow of gas may be injected into a liquid for one or more of several reasons. A reactive gas may be injected into a liquid to react with one or more components of the liquid, such as, for example, the injection of oxygen into molten iron to react with carbon within the molten iron to decarburize the iron and to provide heat to the molten iron. Oxygen may be injected into other molten metals such as copper, lead and zinc for smelting or refining purposes or into an aqueous liquid or hydrocarbon liquid to carry out an oxidation reaction. A non-oxidizing gas, such as an inert gas, may be injected into a liquid to stir the liquid in order to promote, for example, better temperature distribution or better component distribution throughout the liquid.
Sometimes it is desirable to have the gas stream flow for an extended distance at a high velocity such as a supersonic velocity. This can be done by surrounding the gas stream in a flame envelope. The flame envelope keeps ambient gas from aspirating into the gas stream and this leads to the establishment of a coherent gas stream which can flow for an extended distance without any significant decrease in the gas stream velocity or significant increase in the diameter of the gas stream.
It is often desirable to use more than one gas stream in an operation. The gas could be the same for all the gas streams, or different gases could be used for one or more of the gas streams. For example, in electric arc furnace practice or basic oxygen furnace practice it is sometimes preferable to inject oxygen into the molten metal at two or more locations rather than at a single location. Moreover, in electric arc furnace practice it may be desirable to use one or more gas streams for gas injection into the molten metal and, in addition, one or more gas streams to provide oxygen into the head space of the furnace vessel for post combustion.
When in such multiple gas stream practice it is desired that the gas streams also be coherent, this has heretofore been accomplished by using a separate injection lance for each gas stream whereby the gas streams and the fluids for the corresponding flame envelopes for each of the gas streams are provided. While such a system using multiple lances effectively provides multiple coherent gas streams, it is costly and difficult to use. These problems increase as the number of individual lances increases.
Accordingly, it is an object of this invention to provide a system for establishing multiple coherent jets wherein only a single injection lance is required.